Tuberculosis (TB) remains one of the leading causes of morbidity and mortality globally. Both treatment and control of this deadly disease are increasingly hampered by the emergence of mutltidrug resistant (MDR) and more recently extensively drug resistant (XDR) strains of M. tuberculosis, the causative agent of TB. China bears the 2nd highest case burden of TB and the largest number of MDR-TB cases worldwide. In general the TB situation in China is more severe in rural areas. HIV prevalence in China is relatively low however is rising rapidly and will likely lead to more TB and MDR-TB. While poor compliance and/or inadequate TB therapy are clearly involved in the emergence of drug-resistance, the process is complex, likely involving socioeconomic and other patient factors as well. We hypothesize that the high prevalence/incidence of MDR-TB in selected regions of China is inversely associated with the patients'socioeconomic conditions (e.g. poverty, access to healthcare), in addition to medical (e.g. previous TB, HIV) and bacterial (e.g. drug-resistant genotypes) factors. Our overall aims are to describe the MDR-TB situation in rural China and define social or medical determinants that contribute to the ongoing MDR-TB epidemic. We propose to 1) characterize the natural distribution of drug-resistant TB (including MDR-TB) in a well-defined Chinese rural population with high endemic TB;2) carry out a case-control study to determine the biomedical and social determinants that are associated with MDR-TB;and 3) describe the transmission dynamics of drug-resistant TB in rural China. To that end, we will use cross-sectional, case-control and qualitative (Focus Group Discussion) study designs involving field epidemiological, molecular epidemiologic and sociological qualitative methods. The scale of the Chinese MDR-TB problem juxtaposed with rising HIV rates and the emergence of XDR-TB underscores the need to conduct field studies aimed at identifying both proximal and distal factors fueling this epidemic. MDR-TB is associated with high morbidity and mortality. Globally, China bears the largest number of MDR-TB cases that is more severe in rural areas. This scenario can worsen as the HIV rates increase. It is imperative to find not only biological factors but also social factors that more distally fuel this ongoing epidemic. Results of this study can contribute directly to improving TB control strategies aimed at reducing MDR-TB.